Construction of Fe,V-Codoped Ni ₃ S ₂ /V ₂ O ₅ toward Highly Efficient Large Current Density Freshwater/Seawater Splitting

An economical and stable electrocatalyst for alkaline seawater electrolysis plays a crucial role in enabling the industrial-scale production of green hydrogen. Herein, we prepared Fe,V-codoped Ni₃S₂/V₂O₅ with carboxylate groups grown on nickel foam (NF) using hydrothermal and soaking methods, resulting in superior electrocatalytic activity and stability. In alkaline freshwater and seawater electrolytes, the overpotentials of Fe,V-Ni₃S₂/V₂O₅/NF for the hydrogen evolution reaction (HER) are 172 and 259 mV, respectively, while for the oxygen evolution reaction (OER), they are 296 and 363 mV at 1000 mA cm^-2. Notably, the cell voltage of Fe,V-Ni₃S₂/V₂O₅/NF (+,-) required for the electrolysis process is 1.704 V in alkaline freshwater and 1.868 V in seawater at the same current density, and it displays robust durability for over 300 h while maintaining consistent performance, which demonstrates its viability for economical hydrogen generation from seawater at large current density.